Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S263451AbUCTPyz (ORCPT ); Sat, 20 Mar 2004 10:54:55 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S263452AbUCTPyz (ORCPT ); Sat, 20 Mar 2004 10:54:55 -0500 Received: from mion.elka.pw.edu.pl ([194.29.160.35]:49038 "EHLO mion.elka.pw.edu.pl") by vger.kernel.org with ESMTP id S263451AbUCTPyx (ORCPT ); Sat, 20 Mar 2004 10:54:53 -0500 From: Bartlomiej Zolnierkiewicz To: Johannes Stezenbach Subject: Re: [PATCH] barrier patch set Date: Sat, 20 Mar 2004 17:03:30 +0100 User-Agent: KMail/1.5.3 Cc: Matthias Andree , Linux Kernel References: <20040319153554.GC2933@suse.de> <200403200313.05681.bzolnier@elka.pw.edu.pl> <20040320025312.GA12710@convergence.de> In-Reply-To: <20040320025312.GA12710@convergence.de> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200403201703.30403.bzolnier@elka.pw.edu.pl> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1332 Lines: 36 On Saturday 20 of March 2004 03:53, Johannes Stezenbach wrote: > Bartlomiej Zolnierkiewicz wrote: > > On Saturday 20 of March 2004 02:48, Johannes Stezenbach wrote: > > > hdparm -i and -I ultimately both interpret WIN_IDENTIFY result, and > > > both test bit 0x0020 of word 85. So it's unclear to me why they report > > > a different write cache setting. I added a hexdump to dump_identity() > > > in hdparm.c, and found that bit 0x0020 of word 85 is always set. > > > > or WIN_PIDENTIFY to be strict but > > > > -i returns _cached_ (read when the device was probed) identify data > > (uses HDIO_GET_IDENTIFY ioctl) > > -I reads _current_ data directly from the device > > (uses HDIO_DRIVE_CMD ioctl) > > Oh, right. > > But: HDIO_GET_IDENTITY returns drive->id, and surely drive->id > is used internally. So isn't it a bug that drive->id is not > updated when the write cache setting is changed? No, drive->id shouldn't be changed. > I think the barrier code uses drive->id to determine if the > write cache is enabled. The barrier code depends on drive->wcache. Regards, Bartlomiej - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/